Exemplary embodiments of the present invention relate to a light source unit including: an arc tube having a light emitting section in which discharging emission between electrodes is carried out and sealed sections provided at both ends of the light emitting section; an elliptic reflector to emit a luminous flux radiated from the arc tube in a certain direction; a collimator lens to make parallel convergent light from the elliptic reflector, and a projector having the light source unit. The light source unit and the projector according to exemplary embodiments of the present invention can be used, for example, as the light source unit and the projector for multimedia presentation in conferences, academic conferences, exhibitions, and the like.
The related art includes a projector to enlarge and project an optical image by modulating a luminous flux emitted from a light source according to image information. Such a projector is used for presentation in conferences or the like with a personal computer. This type of related art project can be used to view movies on a large screen in a home theater.
The related art includes a light source unit to be used in this type of projector which has a structure including an electric discharging arc tube, such as a metal halide lamp or a high-pressure mercury lamp, and a collimator lens having an elliptic reflector stored in a lamp housing or the like to make parallel convergent light from the reflector.
On the other hand, fixation of the collimator lens to a lens frame with a higher degree of accuracy in the process of assembling the light source unit can enhance miniaturization and accuracy of the light source unit of the projectors. Therefore, it may be necessary to fix an optical axis of the collimator lens and an optical axis of the lens frame in alignment as much as possible, and to reduce or prevent lowering of an illumination intensity caused by displacement between the optical axis of the elliptic reflector and the optical axis of the collimator lens in order to enhance or improve the optical property of the light source unit.
A related art light source unit has a device to fix the collimator lens to the lens frame. This related art technology assembles the lens frame into the light source unit. A device to fix a lens to a lens frame, which is disclosed in related art document JP-A-2000-28887 claim 15, FIG. 1), is employed in assembly of a light source unit (optical lens unit). The lens is retained or fixed to the lens frame formed of thermoplastic resin.
The light source unit obtained from this technology includes a stationary holder to retain the lens frame in an unmovable state, a heating unit to receive heat for melting claws by coming into and out of contact with a heat generating unit, a movable member to be moved along the optical axis of the lens, forming units located at three positions to hold the edge of the lens surface of the lens and melting the claws so as to move toward the centerline of the optical axis of the lens, the forming units to form at substantially regular intervals on a heating surface, so that occurrence of displacement of the optical axis between the lens and the lens frame is reduced or prevented to satisfy required accuracies such as coaxiality of the lenses.
However, in the light source unit (optical lens unit) in the related art, since the device to fix the lens to the lens frame and then to the light source unit is complicated and the shapes of required components are also complicated, there arises such problem that the workability is low and hence the manufacturing cost increases. The light source unit in the related art is subject to another problem in that it is difficult to perform adjustment or fixation as described above for controlling displacement between the optical axes of the elliptic reflector and the collimator lens integrated therein, with high degree of accuracy.